The brazen thief who walked out of a San Francisco art gallery with a quarter-million-dollar Picasso under his arm turned out to be a former wine steward and waiter at high-end Manhattan restaurants BLT Fish and Per Se.

Police said Mark Lugo, 30, flew to San Francisco on the Fourth of July, checked into a pricey hotel and strolled the next morning into the Weinstein Gallery.

Witnesses told cops they saw a man wearing loafers without socks lift from the wall a framed pencil-on-paper sketch done by Picasso in 1965 — leaving more valuable paintings in place — and walk out.

Police traced Lugo to the luxury Hotel Palomar less than a mile away, and picked him up Wednesday at the apartment of friends in Napa.